What type of flow is seen in a normal carotid bulb?

• A. Laminar flow
• B. Turbulent flow/swirling flow within the bulb. Some reversal of flow within bulb is normal
• C. No flow
• D. Pulsatile reverse flow only

Answer: (B)

The key idea is how flow behaves at a vessel bifurcation with expansion. In the carotid bulb, the sudden widening disrupts the smooth, laminar motion of blood and creates flow separation, leading to swirling patterns and local vortices. Because of this geometry, brief reverse flow can occur within the bulb during parts of the cardiac cycle, which is a normal physiologic feature. There is still forward, pulsatile flow moving downstream, but the bulb itself often hosts these disturbed, turbulent-like patterns. So this combination—swirling flow with occasional flow reversal in the bulb region—is the expected behavior in a healthy carotid bulb.